Chick 1 looks a lot like my girl Iris. I'm not seeing any definite indicators of cockerel in that one... At 8 weeks old, most cockerels will have a very pronounced comb, which (in my experience) starts being obvious around 6-7 weeks. Most cockerels will also have a dark mahogany "cape" on their shoulders (but not all cockerels will get a distinctive cape) and a splotchy pattern.
Here's one of my cockerels' combs at 8 weeks...

Chick 2 has a dark mahogany cape... That one's probably a cockerel. One of my EE cockerels looked like that as a chick... He's the one on the left... Not the greatest photo, but oh well. He grew out mostly white with red/mahogany patches. He was gorgeous.

Chick 3, like 1, doesn't have any indicators of cockerel either. Small comb, no cape, and nice pattern. That one's likely a pullet as well.
Here's one of my cockerels' combs at 8 weeks...
Chick 2 has a dark mahogany cape... That one's probably a cockerel. One of my EE cockerels looked like that as a chick... He's the one on the left... Not the greatest photo, but oh well. He grew out mostly white with red/mahogany patches. He was gorgeous.
Chick 3, like 1, doesn't have any indicators of cockerel either. Small comb, no cape, and nice pattern. That one's likely a pullet as well.